HDFS-7473. Document setting dfs.namenode.fs-limits.max-directory-items to 0 is invalid. Contributed by Akira AJISAKA.

(cherry picked from commit d555bb2120cb44d094546e6b6560926561876c10)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -293,6 +293,9 @@ Release 2.7.0 - UNRELEASED
     HDFS-7472. Fix typo in message of ReplicaNotFoundException.
     (Masatake Iwasaki via wheat9)
 
+    HDFS-7473. Document setting dfs.namenode.fs-limits.max-directory-items to 0
+    is invalid. (Akira AJISAKA via cnauroth)
+
 Release 2.6.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java

@@ -242,7 +242,7 @@ public class FSDirectory implements Closeable {
     Preconditions.checkArgument(
         maxDirItems > 0 && maxDirItems <= MAX_DIR_ITEMS, "Cannot set "
             + DFSConfigKeys.DFS_NAMENODE_MAX_DIRECTORY_ITEMS_KEY
-            + " to a value less than 0 or greater than " + MAX_DIR_ITEMS);
+            + " to a value less than 1 or greater than " + MAX_DIR_ITEMS);
 
     int threshold = conf.getInt(
         DFSConfigKeys.DFS_NAMENODE_NAME_CACHE_THRESHOLD_KEY,

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -314,7 +314,8 @@
   <name>dfs.namenode.fs-limits.max-directory-items</name>
   <value>1048576</value>
   <description>Defines the maximum number of items that a directory may
-      contain.  A value of 0 will disable the check.</description>
+      contain. Cannot set the property to a value less than 1 or more than
+      6400000.</description>
 </property>
 
 <property>